Centre for the Developing Brain, King's College London, London, UK.
Biomedical Engineering Department, King's College London, London, UK.
Magn Reson Med. 2018 Mar;79(3):1447-1459. doi: 10.1002/mrm.26810. Epub 2017 Jun 26.
To develop a purpose-built quiet echo planar imaging capability for fetal functional and diffusion scans, for which acoustic considerations often compromise efficiency and resolution as well as angular/temporal coverage.
The gradient waveforms in multiband-accelerated single-shot echo planar imaging sequences have been redesigned to minimize spectral content. This includes a sinusoidal read-out with a single fundamental frequency, a constant phase encoding gradient, overlapping smoothed CAIPIRINHA blips, and a novel strategy to merge the crushers in diffusion MRI. These changes are then tuned in conjunction with the gradient system frequency response function.
Maintained image quality, SNR, and quantitative diffusion values while reducing acoustic noise up to 12 dB (A) is illustrated in two adult experiments. Fetal experiments in 10 subjects covering a range of parameters depict the adaptability and increased efficiency of quiet echo planar imaging.
Purpose-built for highly efficient multiband fetal echo planar imaging studies, the presented framework reduces acoustic noise for all echo planar imaging-based sequences. Full optimization by tuning to the gradient frequency response functions allows for a maximally time-efficient scan within safe limits. This allows ambitious in-utero studies such as functional brain imaging with high spatial/temporal resolution and diffusion scans with high angular/spatial resolution to be run in a highly efficient manner at acceptable sound levels. Magn Reson Med 79:1447-1459, 2018. © 2017 The Authors Magnetic Resonance in Medicine published by Wiley Periodicals, Inc. on behalf of International Society for Magnetic Resonance in Medicine. This is an open access article under the terms of the Creative Commons Attribution NonCommercial License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited and is not used for commercial purposes.
为胎儿功能和扩散扫描开发专用静音回波平面成像能力，由于声学考虑因素通常会影响效率和分辨率以及角度/时间覆盖范围。
多带加速单次回波平面成像序列中的梯度波形已重新设计，以最小化频谱含量。这包括具有单个基频的正弦读出、恒定相位编码梯度、重叠平滑的 CAIPIRINHA 闪烁、以及在扩散 MRI 中合并破碎机的新策略。然后，这些变化与梯度系统频率响应函数一起进行调整。
在两个成人实验中，保持了图像质量、信噪比和定量扩散值，同时将声噪声降低了 12dB（A）。在 10 个涵盖各种参数的受试者的胎儿实验中，描绘了静音回波平面成像的适应性和效率提高。
专为高效的多带胎儿回波平面成像研究而设计，所提出的框架降低了所有基于回波平面成像的序列的声噪声。通过调谐到梯度频率响应函数进行全面优化，可以在安全限制内以最大的时间效率进行扫描。这使得在可接受的声级下以高空间/时间分辨率进行功能脑成像和具有高角度/空间分辨率的扩散扫描等雄心勃勃的宫内研究能够以高效的方式进行。磁共振医学 79:1447-1459,2018.©2017 作者磁共振医学由 Wiley 期刊出版公司代表国际磁共振医学学会出版。这是在知识共享署名非商业许可下的条款下许可使用、分发和复制的原创作品，前提是原始作品正确引用并且不用于商业目的。
